Insect Gas Exchange Flashcards
(18 cards)
Why do insects have an exoskeleton and what is it made out of?
Made out of chitin (a hard fibrous material) to help with protection
Lipid layer to prevent water loss
Do insects have lungs?
no- they have a tracheal system
Insect adaptations to prevent water loss?
Small SA:V ratio- where water can evaporate from
Waterproof exoskeleton
Spiracles- gases enter and water can evaporate from- they open and close to reduce water loss
What are spiracles?
Round, valve like openings running along the length of the abdomen
What enters and exits via the spiracles?
oxygen and carbon dioxide.
What is the trachea?
A network of internal tubes
Why do the trachea tubes have rings within them?
To strengthen the tubes and keep them open
What are tracheoles?
The trachea branch into smaller tubes, deeper into the abdomen
They extend throughout all the tissues to deliver oxygen to all respiring cells
What are the 3 methods of moving gases into he tracheal system?
Diffusion
Abdominal pumping
Anaerobic respiration
Diffusion?
Gas can exchange by diffusion
When cells respire, they use up oxygen and produce carbon dioxide- creating a conc gradient from the tracheoles to the atmosphere
Abdominal pumping?
An insect contracts and relaxes their abdominal muscles to move gases
Changes the volume and gas pressure in the tracheal network
Anaerobic respiration?
When the insects are flying, the muscle cells start to respire anaerobically to produce lactic acid
This lowers the water potential of the cells so water moves from the tracheoles into the cells by osmosis
This decreases the volume int he tracheaoles so more air from the atmosphere is drawn in
Adaptations for efficient diffusion?
Large number of tracheoles and spiracles- large SA
Tracheole walls are thin and short distance between spiracles and tracheoles- short diffusion distance
Use of oxygen and CO2 being produced produces steep diffusion gradients
Describe the pathway of oxygen from the air to a respiring cell in an insect?
Air travels through the spiracle into the trachea and then into the tracheoles
Diffuses through the layer of water into the respiring cell
Flexible walled chambers?
Linked to the trachea- fill with air during abdominal pumping- greater volume of air movement
Sunken spiracles?
Reduced effect of wind to maintain a high conc of water vapour
Sphincter?
Rings of muscles that change the diameter
Contract to decrease the diameter and water loss- decreased gas exchange
Why are insect spiracles often surrounded by hair?
The hairs trap a layer of air which has a high conc of water vapour- there is a smaller conc gradient of water vapour so less water is lost from the cell
